Well if he at least took something from that and became a better person thanks to this experience then who are we to judge?
Everyone will be ashamed of what they have done in the past. I was ashamed of myself in the past as well because I used to spend a huge amount to gamble every single day, sometimes I win and ended up losing everything again. I was very stupid before and now I regret it , which is why now I only gamble for fun
It's not that easy to move on rom the past especially if it affects you deeply, for example, being addicted to gambling you managed to destroy your relationship towards family, girlfriend/boyfriend, friends, etc. Not caring about anything at all because of gambling. That's why it's shameful, you should learn how to stop it and pray to God that he save you but its all up to you really.